The present invention relates to knives or similar tools having a handle and one or more blades or other implements pivotally movable between folded and extended positions with respect to the handle, and means for releasably locking each implement in the fully open position. More specifically, the invention relates to improvements in the design of tools having pivoted, lockable implements and featuring a unitary liner-beam spring element mounted in a recess on the inner side of a molded cover piece of the handle.
U.S. Pat. Nos. 4,805,303 and 5,044,079, both of the present inventor, disclose multi-blade, folding knives of the so-called lockback type. When a blade of such knives is pivoted to the fully open position, a pivotally mounted locking member is moved by the biasing force of a beam spring into mechanically locking engagement with a notch in the blade to prevent movement away from this position until the locking member is manually rotated against the biasing force of the beam spring. The knives of both patents include metal liners mounted in face-to-face engagement with the inner opposing surfaces of the handle cover pieces for purposes of strength and rigidity.
The locking feature of the knives of the aforementioned patents, as well as other prior art knives of this type, while desirable for safety purposes, adds to the number of parts, and thus to the cost of both parts and assembly. Also, knives or similar tools having lockback features are generally larger and heavier than their non-locking counterparts.
Accordingly, it is a principal object of the present invention to provide a folding knife, or similar hand tool, with lockback features which is generally smaller, lighter and more economical in both materials and assembly costs than prior art tools having such features.
Another object is to provide a hand tool having at least one implement movable with respect to a handle between folded and extended positions, and a spring biased locking member preventing movement of the implement away from the extended position until released, wherein a relatively large implement is accommodated by a relatively small handle. That is, the blade or other folding implement is larger relative to the handle than prior art folding tools with lockback features.
Other objects will in part be obvious and will in part appear hereinafter.